Treat unstable lints as unknown

This change causes unstable lints to be ignored if the `unknown_lints` lint is allowed. To achieve this, it also changes lints to apply as soon as they are processed. Previously, lints in the same set were processed as a batch and then all simultaneously applied. Implementation of rust-lang/compiler-team#469

Author: djkoloski

compiler/rustc_feature/src/active.rs

@@ -169,6 +169,8 @@ declare_features! (
  (active, staged_api, "1.0.0", None, None),
  /// Added for testing E0705; perma-unstable.
  (active, test_2018_feature, "1.31.0", None, Some(Edition::Edition2018)),
+ /// Added for testing unstable lints; perma-unstable.
+ (active, test_unstable_lint, "1.60.0", None, None),
  /// Allows non-`unsafe` —and thus, unsound— access to `Pin` constructions.
  /// Marked `incomplete` since perma-unstable and unsound.
  (incomplete, unsafe_pin_internals, "1.60.0", None, None),

compiler/rustc_lint/src/levels.rs

@@ -93,10 +93,21 @@ impl<'s> LintLevelsBuilder<'s> {
  self.store
  }
 
+ fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
+ &self.sets.list[self.cur].specs
+ }
+
+ fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource> {
+ &mut self.sets.list[self.cur].specs
+ }
+
  fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
- let mut specs = FxHashMap::default();
  self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
 
+ self.cur = self.sets.list.push(LintSet {
+ specs: FxHashMap::default(),
+ parent: COMMAND_LINE,
+ });
  for &(ref lint_name, level) in &sess.opts.lint_opts {
  store.check_lint_name_cmdline(sess, &lint_name, level, self.registered_tools);
  let orig_level = level;
@@ -108,30 +119,28 @@ impl<'s> LintLevelsBuilder<'s> {
  };
  for id in ids {
  // ForceWarn and Forbid cannot be overriden
- if let Some((Level::ForceWarn | Level::Forbid, _)) = specs.get(&id) {
+ if let Some((Level::ForceWarn | Level::Forbid, _)) = self.current_specs().get(&id) {
  continue;
  }
 
- self.check_gated_lint(id, DUMMY_SP);
- let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
- specs.insert(id, (level, src));
+ if self.check_gated_lint(id, DUMMY_SP) {
+ let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
+ self.current_specs_mut().insert(id, (level, src));
+ }
  }
  }
-
- self.cur = self.sets.list.push(LintSet { specs, parent: COMMAND_LINE });
  }
 
  /// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
  /// (e.g. if a forbid was already inserted on the same scope), then emits a
  /// diagnostic with no change to `specs`.
  fn insert_spec(
  &mut self,
- specs: &mut FxHashMap<LintId, LevelAndSource>,
  id: LintId,
  (level, src): LevelAndSource,
  ) {
  let (old_level, old_src) =
- self.sets.get_lint_level(id.lint, self.cur, Some(&specs), &self.sess);
+ self.sets.get_lint_level(id.lint, self.cur, Some(self.current_specs()), &self.sess);
  // Setting to a non-forbid level is an error if the lint previously had
  // a forbid level. Note that this is not necessarily true even with a
  // `#[forbid(..)]` attribute present, as that is overriden by `--cap-lints`.
@@ -154,7 +163,7 @@ impl<'s> LintLevelsBuilder<'s> {
  };
  debug!(
  "fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
- fcw_warning, specs, old_src, id_name
+ fcw_warning, self.current_specs(), old_src, id_name
  );
 
  let decorate_diag = |diag: &mut Diagnostic| {
@@ -213,9 +222,9 @@ impl<'s> LintLevelsBuilder<'s> {
  }
  }
  if let Level::ForceWarn = old_level {
- specs.insert(id, (old_level, old_src));
+ self.current_specs_mut().insert(id, (old_level, old_src));
  } else {
- specs.insert(id, (level, src));
+ self.current_specs_mut().insert(id, (level, src));
  }
  }
 
@@ -239,7 +248,11 @@ impl<'s> LintLevelsBuilder<'s> {
  is_crate_node: bool,
  source_hir_id: Option<HirId>,
  ) -> BuilderPush {
- let mut specs = FxHashMap::default();
+ let prev = self.cur;
+ self.cur = self.sets.list.push(LintSet {
+ specs: FxHashMap::default(),
+ parent: prev,
+ });
  let sess = self.sess;
  let bad_attr = |span| struct_span_err!(sess, span, E0452, "malformed lint attribute input");
  for (attr_index, attr) in attrs.iter().enumerate() {
@@ -348,8 +361,9 @@ impl<'s> LintLevelsBuilder<'s> {
  reason,
  );
  for &id in *ids {
- self.check_gated_lint(id, attr.span);
- self.insert_spec(&mut specs, id, (level, src));
+ if self.check_gated_lint(id, attr.span) {
+ self.insert_spec(id, (level, src));
+ }
  }
  if let Level::Expect(expect_id) = level {
  self.lint_expectations
@@ -368,7 +382,7 @@ impl<'s> LintLevelsBuilder<'s> {
  reason,
  );
  for id in ids {
- self.insert_spec(&mut specs, *id, (level, src));
+ self.insert_spec(*id, (level, src));
  }
  if let Level::Expect(expect_id) = level {
  self.lint_expectations
@@ -378,7 +392,7 @@ impl<'s> LintLevelsBuilder<'s> {
  Err((Some(ids), ref new_lint_name)) => {
  let lint = builtin::RENAMED_AND_REMOVED_LINTS;
  let (lvl, src) =
- self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
+ self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), &sess);
  struct_lint_level(
  self.sess,
  lint,
@@ -408,7 +422,7 @@ impl<'s> LintLevelsBuilder<'s> {
  reason,
  );
  for id in ids {
- self.insert_spec(&mut specs, *id, (level, src));
+ self.insert_spec(*id, (level, src));
  }
  if let Level::Expect(expect_id) = level {
  self.lint_expectations
@@ -449,7 +463,7 @@ impl<'s> LintLevelsBuilder<'s> {
  CheckLintNameResult::Warning(msg, renamed) => {
  let lint = builtin::RENAMED_AND_REMOVED_LINTS;
  let (renamed_lint_level, src) =
- self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
+ self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), &sess);
  struct_lint_level(
  self.sess,
  lint,
@@ -473,7 +487,7 @@ impl<'s> LintLevelsBuilder<'s> {
  CheckLintNameResult::NoLint(suggestion) => {
  let lint = builtin::UNKNOWN_LINTS;
  let (level, src) =
- self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
+ self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), self.sess);
  struct_lint_level(self.sess, lint, level, src, Some(sp.into()), |lint| {
  let name = if let Some(tool_ident) = tool_ident {
  format!("{}::{}", tool_ident.name, name)
@@ -504,8 +518,9 @@ impl<'s> LintLevelsBuilder<'s> {
  {
  let src = LintLevelSource::Node(Symbol::intern(&new_name), sp, reason);
  for &id in ids {
- self.check_gated_lint(id, attr.span);
- self.insert_spec(&mut specs, id, (level, src));
+ if self.check_gated_lint(id, attr.span) {
+ self.insert_spec(id, (level, src));
+ }
  }
  if let Level::Expect(expect_id) = level {
  self.lint_expectations
@@ -519,7 +534,7 @@ impl<'s> LintLevelsBuilder<'s> {
  }
 
  if !is_crate_node {
- for (id, &(level, ref src)) in specs.iter() {
+ for (id, &(level, ref src)) in self.current_specs().iter() {
  if !id.lint.crate_level_only {
  continue;
  }
@@ -530,7 +545,7 @@ impl<'s> LintLevelsBuilder<'s> {
 
  let lint = builtin::UNUSED_ATTRIBUTES;
  let (lint_level, lint_src) =
- self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
+ self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), self.sess);
  struct_lint_level(
  self.sess,
  lint,
@@ -551,9 +566,9 @@ impl<'s> LintLevelsBuilder<'s> {
  }
  }
 
- let prev = self.cur;
- if !specs.is_empty() {
- self.cur = self.sets.list.push(LintSet { specs, parent: prev });
+ if self.current_specs().is_empty() {
+  self.sets.list.pop();
+ self.cur = prev;
  }
 
  BuilderPush { prev, changed: prev != self.cur }
@@ -574,18 +589,25 @@ impl<'s> LintLevelsBuilder<'s> {
  }
 
  /// Checks if the lint is gated on a feature that is not enabled.
- fn check_gated_lint(&self, lint_id: LintId, span: Span) {
+ ///
+ /// Returns `true` if the lint's feature is enabled.
+ fn check_gated_lint(&self, lint_id: LintId, span: Span) -> bool {
  if let Some(feature) = lint_id.lint.feature_gate {
  if !self.sess.features_untracked().enabled(feature) {
- feature_err(
- &self.sess.parse_sess,
- feature,
- span,
- &format!("the `{}` lint is unstable", lint_id.lint.name_lower()),
- )
- .emit();
+ let (unknown_lints_level, _) = self.lint_level(builtin::UNKNOWN_LINTS);
+ if unknown_lints_level != Level::Allow {
+ feature_err(
+ &self.sess.parse_sess,
+ feature,
+ span,
+ &format!("the `{}` lint is unstable", lint_id.lint.name_lower()),
+ )
+ .emit();
+ }
+ return false;
  }
  }
+ true
  }
 
  /// Called after `push` when the scope of a set of attributes are exited.

compiler/rustc_lint_defs/src/builtin.rs

@@ -3128,6 +3128,7 @@ declare_lint_pass! {
  SUSPICIOUS_AUTO_TRAIT_IMPLS,
  UNEXPECTED_CFGS,
  DEPRECATED_WHERE_CLAUSE_LOCATION,
+ TEST_UNSTABLE_LINT,
  ]
 }
 
@@ -3771,3 +3772,11 @@ declare_lint! {
  Warn,
  "deprecated where clause location"
 }
+
+declare_lint! {
+ #[doc(hidden)]
+ pub TEST_UNSTABLE_LINT,
+ Deny,
+ "this unstable lint is only for testing",
+ @feature_gate = sym::test_unstable_lint;
+}

compiler/rustc_span/src/symbol.rs

@@ -1383,6 +1383,7 @@ symbols! {
  test_case,
  test_removed_feature,
  test_runner,
+ test_unstable_lint,
  then_with,
  thread,
  thread_local,

src/test/ui/unknown-unstable-lints/allow-unknown-unstable-lint-command-line.rs

@@ -0,0 +1,4 @@
+// check-pass
+// compile-flags: -Aunknown_lints -Atest_unstable_lint
+
+fn main() {}

src/test/ui/unknown-unstable-lints/allow-unknown-unstable-lint-inline.rs

@@ -0,0 +1,5 @@
+// check-pass
+
+#![allow(unknown_lints, test_unstable_lint)]
+
+fn main() {}

src/test/ui/unknown-unstable-lints/unstable-lint-command-line.rs

@@ -0,0 +1,5 @@
+// check-fail
+// compile-flags: -Atest_unstable_lint
+// error-pattern: the `test_unstable_lint` lint is unstable
+
+fn main() {}

src/test/ui/unknown-unstable-lints/unstable-lint-command-line.stderr

@@ -0,0 +1,11 @@
+error[E0658]: the `test_unstable_lint` lint is unstable
+ |
+ = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
+
+error[E0658]: the `test_unstable_lint` lint is unstable
+ |
+ = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/unknown-unstable-lints/unstable-lint-inline.rs

@@ -0,0 +1,6 @@
+// check-fail
+// error-pattern: the `test_unstable_lint` lint is unstable
+
+#![allow(test_unstable_lint)]
+
+fn main() {}

src/test/ui/unknown-unstable-lints/unstable-lint-inline.stderr

@@ -0,0 +1,19 @@
+error[E0658]: the `test_unstable_lint` lint is unstable
+ --> $DIR/unstable-lint-inline.rs:4:1
+ |
+LL | #![allow(test_unstable_lint)]
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
+
+error[E0658]: the `test_unstable_lint` lint is unstable
+ --> $DIR/unstable-lint-inline.rs:4:1
+ |
+LL | #![allow(test_unstable_lint)]
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.